Structural protection system for buildings

ABSTRACT

An energy dissipation system for structural protection of buildings includes at least one structure with a base, a second base fixed to the ground, an energy dissipation device, and a lever mechanism. The structure opposes seismic actions by translating horizontal displacement into vertical displacement. The lever mechanism amplifies displacement of the energy dissipation device in response to vertical displacement of the structure.

RELATED APPLICATIONS

The present application is a divisional application of U.S. patent application Ser. No. 13/395,185 filed Mar. 9, 2012, titled “STRUCTURAL PROTECTION SYSTEM FOR BUILDINGS,” the entire disclosure of which is incorporated by reference herein.

The present application is based on, and claims priority from PCT International Application No. PCT/EP2010/062748, filed Aug. 31, 2010, the entire disclosure of which is incorporated by reference herein.

The present application is based on, and claims priority from Italian Provisional Application No. MC2009A000195, filed Sep. 10, 2009, the entire disclosure of which is incorporated by reference herein.

BACKGROUND

The present application relates to a structural system for seismic protection of buildings. The structural system according to the present application is especially suitable for seismic protection of existing buildings, with special reference to buildings that play an important social role, classified as strategic buildings (hospitals, schools, barracks, etc.) and also of new buildings.

FIG. 1 illustrates a structural system for seismic protection of buildings according to the prior art. A plurality of dissipation devices (1) is installed in building (E) to be protected, being designed to dissipate the energy generated by the oscillations of the building due to earth tremor. According to the different techniques, said dissipation devices (1) are installed inside the building (E) or outside it on the walls.

The building (E) comprises a framework of the bearing structure. A framework is a frame composed of multiple floors (S) and vertical elements (P), such as pillars or bearing walls, in order to generate a plurality of spaces (M).

At least one dissipation device (1) is installed in each space (M) of said framework, in bracing configuration, preferably with diagonal direction with respect to the space (M). Each dissipation device comprises a dissipation means (1 c) disposed between two rigid rods. A first end (1 a) of the first rod of the dissipation device is tied to a portion of angle between the lower floor (S) of the space and a first lateral wall of the building. A second end (1 a) of the second rod of the dissipation device is tied to a portion of angle between the upper floor (S) of the space and a second intermediate wall of the building.

Therefore each dissipation device (1) works autonomously and contributes to compensate wall deformations of each space (M) of the framework.

Such a structural system is impaired by a series of drawbacks due to the fact that the dissipation devices (1) must be disposed inside the building.

BRIEF DESCRIPTION OF THE DRAWINGS

The present systems are illustrated by way of example, and not by limitation, in the figures of the accompanying drawings, wherein elements having the same reference numeral designations represent like elements throughout and wherein:

FIG. 1 is a diagrammatic cross-sectional view along a vertical plane that shows a structural system for seismic protection of buildings according to the prior art;

FIG. 2 is a diagrammatic cross-sectional view along a vertical plane that shows, in some embodiments, a structural system for seismic protection of buildings with a distributed energy dissipation system;

FIG. 3 is a diagrammatic cross-sectional view along a vertical plane that shows, in some embodiments, a structural system with an energy dissipation system concentrated at the base;

FIG. 4 is a plan view of the structural system of FIG. 3;

FIG. 5 is a perspective view of the structural system of FIG. 3;

FIG. 6 is a diagrammatic cross-sectional view along a vertical plane that shows, in some embodiments, a structural system which provides for a lever mechanism that multiplies the travel of the energy dissipation device;

FIG. 6A is an enlarged view of the detail contained in circle (A) of FIG. 6.

FIG. 7 is the same view as FIG. 6 showing the oscillation of the structural system of FIG. 6 during earth tremor;

FIG. 7 A is an enlarged view of the details contained in circles (A) and (A′) of FIG. 7;

FIGS. 8 and 9 are two side elevation views that show, in some embodiments, a structural system including a planar frame;

FIG. 10 is a plan view of the structural systems of FIGS. 8 and 9;

FIG. 11 is a cross-sectional view along a vertical plane that shows a specialized structure, in some embodiments, disposed as a nucleus inside a building;

FIGS. 12 and 12A are two side elevation views that show, in some embodiments, a structural system including a column;

FIG. 13 is a plan view of the structural system of FIG. 12; and

FIG. 14 is a perspective view of the structural system of FIG. 12.

DETAILED DESCRIPTION

The purpose of the present application is to eliminate the drawbacks of the prior art by disclosing a structural system that is able to oppose the oscillations of buildings due to earth tremor in an efficient and efficacious way. Another purpose of the present application is to provide such a structural system for seismic protection of buildings that is versatile and at the same time easy to make, install and maintain.

According to the application, the building to be seismically protected is combined with a specialized structure designed to oppose seismic actions by dissipating energy. In cases of existing buildings, the specialized structures can be simply installed in external positions, without having to carry out any works inside the building.

In various embodiments, the specialized structure can comprise a tower or frame or column with suitable rigidity, connected to the building by means of rigid rods with two hinges normally disposed at each floor level. Hereinafter, for the sake of simplicity and without limitation, reference will be always made to a specialized structure that consists in a tower.

The tower is tied at the base with a spherical joint or hinge. Therefore, the tower is free to oscillate in any direction around the spherical joint, rotating and pivoting on the joint (center of rotation). Dissipation devices or dampers are applied around the base of the tower, which strongly oppose the rotation and oscillation of the tower, thus suffering movements and dissipating energy by means of hysteresis cycles.

To amplify displacements (travel: elongation and shortening) of the dissipation devices, suitable mechanisms that operate by means of crank gears can be provided.

The global dissipation system, which is concentrated at the base of the tower, can be of any type.

Therefore, the main function of the tower is to oppose the effects produced by earth tremor by dissipating energy in the specialized area where dissipation devices of generic type (dampers) are installed.

The re-centering (balancing) of the tower is guaranteed by the elasticity of the building structure and also by elastic elements that can be connected in parallel to the energy dissipation means.

In new buildings the tower that acts as seismic-resistant-dissipation element can be inserted inside the building (for example in the stairwell-elevator area).

The structural system of the present application has several advantages compared to known systems. Considerable cost reduction is obtained compared to traditional systems that are made inside the buildings and require additional works in addition to structural works.

If the external seismic-resistant-dissipation structure is of a spatial type (tower), it can provide additional usable volume (enlargement), no longer being an end in itself (of structural type only) and with lower incidence of the seismic adaptation cost. Such a seismic-resistant-dissipation structure can be, for example, a vertical connection element (stairs, elevator) or emergency staircase. Reference is made to the frequent installation of steel emergency staircases outside public buildings, which can also represent a seismic protection element if designed with the structural system of the present application.

Maintenance of dissipation devices can be carried out without interrupting the use of the building during maintenance works, consequently reducing the costs caused by the temporary lack of use.

Installation of the specialized structure can be carried out without interrupting the ordinary use of the building to be protected.

Dissipation devices are concentrated in a single specialized area with limited dimensions (tower base), which is consequently easy to inspect and maintain. For very high buildings the specialized dissipation area can be also positioned at higher levels, not only at the base of the tower.

The dissipation system of the present application guarantees high efficiency, taking full advantage of the devices, and high efficacy of the seismic-resistant devices that are concentrated in a single specialized area compared to the known methods with devices disseminated on the building, the operation of which is affected by the uncertain seismic reaction of the building as a whole, especially due to the presence of non-structural elements (walls in general, etc.).

The rigidity of external seismic-resistant structures with vertical development (tower, frame, column) connected by means of rigid rods to the building is such that it regularizes the deformation (horizontal floor displacements) of the building that is subject to earth tremor, which is generally irregular.

Complete reversibility of the system is guaranteed because no alterations are made to the building, as in case of internal works.

In case of hospital or school buildings, if the structural system of the present application has been correctly studied from an architectural viewpoint, it can provide improved design and improved operation with the use of additional structures (new spaces, services, etc.). This is made possible also because of the high formal flexibility of additional structures. For example, the tower can have a square, rectangular, polygonal, circular, etc. shape, can have a constant height, or can be tapered vertically.

Now referring to FIG. 2, a first embodiment of the structural system for seismic protection of buildings according to the present application is disclosed.

The building (E) to be protected comprises a plurality of levels defined by floors (S) disposed according to horizontal planes. The structural system of the application comprises at least one bearing structure (2) rigidly connected to the building (E).

The bearing structure (2) has basically the same height as the building (E) and is rigidly connected to the building by means of a plurality of rigid rods (3). The rod (3) is provided with a first end (3 a) tied to a wall of the building (E) and a second end (3 b) tied to the bearing structure (2).

In some embodiments, the bearing structure (2) is provided with a plurality of horizontal reinforcement elements (S′) disposed at the same height as the floors (S) of the building (E). In some embodiments, the rigid rods (3) are disposed according to horizontal straight lines on the floors (S) of the building and the corresponding reinforcement elements (S′) of the bearing structure.

The bearing structure (2) is a specialized structure that comprises an energy dissipation system adapted to dissipate the energy of the oscillations suffered by the bearing structure (2) due to earth tremor.

It must be noted that the specialized structure (2) is rigidly connected to the building (E). Therefore the energy dissipation system of the specialized structure is able to compensate and damp also the oscillations suffered by the building (E) during the shocks.

According to the embodiment of FIG. 2, the specialized structure (2) is a tower disposed outside the building (E) and the horizontal reinforcement elements are floors (S′) of the tower disposed between a first vertical wall (2 a) facing the building (E) and a second vertical wall (2 b) opposite the first vertical wall (2 a). In this way a vertical row of parallelepiped spaces (V) is defined in the tower (2).

One dissipation device (1) is disposed in each space (V) of the tower (2), in bracing configuration, diagonally, in such a way to generate an energy dissipation system of the specialized structure (2) distributed along the entire height of the specialized structure.

The dissipation device comprises an energy dissipation means (1 c) disposed between two rigid rods. The energy dissipation means (1 c) can be, for example, a chamber with fluid. A shock-absorbing element, such as elastic means, spring means or damper can be disposed in parallel position to the energy dissipation means (1 c).

In each space (V) the dissipation device (1) comprises:

-   a first end (1 a) tied to a portion of angle between the lower floor     (S′) of the space (V) and the first lateral wall (2 a) of the tower,     and -   a second end (1 a) tied to a portion of angle between the upper     floor (S′) of the space (V) and the second lateral wall (2 a) of the     tower.

In the following description, identical elements or elements corresponding to elements that have already been described are indicated with the same reference numerals, omitting their detailed description.

FIGS. 3-5 describe embodiments of the structural system of the present application wherein the dissipation system is concentrated at the base of the tower (2).

In such embodiments, the base of the tower (2) is tied to a spherical joint or hinge (4) mounted on a base (B) fixed to the ground. The vertical axis of the tower (2) passes through the center of the spherical joint (4).

A plurality of dissipation devices (1) is disposed in peripheral position around the spherical joint (4). Each dissipation device (1) is provided with a first end (1 a) tied to the base (B) and a second end (1 b) tied at the base of the tower. In some embodiments, the tower (2) has a base (20) shaped as overturned pyramid, wherein the vertex of the pyramid is tied to the spherical joint (4).

As shown in FIG. 4, in some embodiments, to protect the rectangular building (E), two specialized structures (2) are sufficient, being disposed in the long opposite sides of the building, near the opposite angles of the building.

The connection system of the tower (2) to the building (E) comprises four rigid rods (3) in each floor, disposed in W-configuration with three connection hinges (3 a) on the building (E) and two connection hinges (3 b) on the tower.

As shown in FIG. 5, in some embodiments, each tower (2) is damped by eight dissipation devices (1) disposed at the four angles of the tower base and along the central lines of the four sides of the tower base.

Referring to FIGS. 6, 6A, 7, and 7 A, in some embodiments, an energy dissipation system is described.

As shown in FIG. 6A, in some embodiments, each dissipation device (1) is connected to a lever mechanism (5) to multiply the travel of the dissipation device (1), i.e. elongation/shortening of the dissipation device (1) to compensate the oscillation of the tower (2).

The lever mechanism (5) comprises two levers (L1, L2). The first lever (L1) is pivoted in the central point (F1) to a projection (51) of a flange (50) tied to the base (B). The second lever (L2) has a first end (La) pivoted at a projection of a flange (52) tied to the base (20) of the tower and a second end (Lb) pivoted at one end of the first lever (L1).

The dissipation device (1) has a first end (1 a) pivoted at a projection of the flange (52) tied to the base (20) of the tower and a second end (1 b) pivoted at the other end of the first lever (L1).

In idle state the dissipation device (1) is basically as long as the second lever (L2) and parallel to the second lever (L2) in such a way that first lever (L1), second lever (L2), flange (52), and dissipation device (1) form an articulated quadrilateral that can oscillate around the fulcrum (F1).

Referring to FIGS. 7 and 7A, when the building (E) suffers oscillation due to earth tremor, also the tower (2) that is rigidly tied to the building (E) suffers oscillation with horizontal displacement (δ_(O)) of the top of the tower.

Consequently, the base (20) of the tower suffers a vertical displacement (δ_(V)) that must be damped and compensated by the dissipation devices (1).

If Li is the length of dissipation device (1) in idle state and Lf is the length of the dissipation device after compression or elongation due to oscillation of the tower, the travel of the dissipation device is determined by the relationship:

δ_(D) =|Li−Lf|

The travel (δ_(D)) of the dissipation device is related to the lever mechanism (5) and vertical displacement (δ_(V)) of the tower base.

(b1) is the distance between the fulcrum (F1) of the first lever (L1) and the fulcrum (Lb) of the second lever (L2) with the first lever (L1). (b2) is the distance between the fulcrum (F1) of the first lever (L1) and the fulcrum (1 b) of the dissipation device (1) with the first lever (L1).

As shown in FIG. 7A, the travel of the dissipation device is determined by the relationship:

δ_(D) =|Li−Lf|=δ _(V)*(1+b2/b1)

If the fulcrum (F1) is in the center of the first lever (L1), i.e. (b1=b2), the travel of the dissipation device is:

δ_(D)=2*δ_(V)

In this case, the elongation or shortening of the dissipation device (1) is twice the vertical displacement (δ_(V)) of the base (20) of the tower.

Referring to FIGS. 8, 9 and 10, in some embodiments, a structural system of the present application is disclosed wherein the specialized structure is a planar frame (102) composed, for example, of a reticular framework.

Also, in such embodiments, the dissipation devices (1) can be disposed at the base of the frame (102). The frame (102) is tied to the ground by means of a planar hinge (104) instead of a spherical joint.

As shown in FIG. 10, in some embodiments, to protect a rectangular building, four frameworks (102) are necessary, being disposed in the four sides of the building.

FIGS. 3, 5, 6, 7, 8, and 9 show embodiments in which five-story buildings and specialized structures (2; 102) are provided with an energy dissipation system concentrated only at the base of the structure.

However, in various embodiments including taller buildings, each specialized structure is made of multiple overlapped parts that are mutually tied by means of a central hinge around which the dissipation devices are disposed. The connection between the various parts of the bearing structure is exactly made as the connection of the base of the bearing structure to the ground.

Referring to FIG. 11, in some embodiments in which a new building (E) is built, the specialized structure (202) is the nucleus of the building: a tower inside the building that is rigidly connected to the internal walls of the building.

In such embodiments, the tower (202) is provided with a specialized energy dissipation system, such as the systems described in the aforementioned embodiments.

Referring to FIGS. 12 12A, 13, and 14, in some embodiments, a a structural system of the present application is described wherein the specialized structure is a column (302).

Also, in such embodiments, the dissipation devices (1) can be disposed at the base of the column (302). The column (302) is anchored to the ground by means of a spherical joint (4).

FIG. 12 A shows an embodiment of the present application in which the base of the column (302) is a horizontal plane under which the dissipation devices (1) and relevant multiplier lever mechanisms (5) are mounted.

As shown in FIGS. 13 and 14, in some embodiments, to protect a rectangular building, five columns (302) are necessary, being disposed in a row on the two long sides of the building. The columns (302) are mutually connected by means of rigid rods (303).

While the foregoing written description enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The disclosure should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the disclosure. 

What is claimed is:
 1. An energy dissipation system comprising: a first base of a structure configured to oppose seismic actions by translating horizontal displacement into vertical displacement; a second base fixed to the ground; an energy dissipation device; and a lever mechanism configured to multiply travel of the energy dissipation device in response to vertical displacement of the structure.
 2. The system of claim 1, wherein the lever mechanism comprises: a first lever pivoted at a fulcrum at the second base; and a second lever, each of the second lever and the energy dissipation device having a first end pivoted at the first base and a second end pivoted at the first lever.
 3. The system of claim 2, wherein the fulcrum is in the center of the first lever such that travel of the energy dissipation device is twice the vertical displacement of the structure.
 4. The system of claim 2, wherein: a first distance is the distance along the first lever from the fulcrum to the second lever; a second distance is the distance along the first lever from the fulcrum to the energy dissipation device; the lever mechanism is further configured such that travel of the energy dissipation device relative to vertical displacement of the structure is a function of the ratio of the second distance to the first distance.
 5. The system of claim 1, wherein the energy dissipation device comprises an energy dissipation means disposed between two rigid rods.
 6. The system of claim 5, wherein the energy dissipation means is a chamber with fluid.
 7. The system of claim 1, wherein translating horizontal displacement into vertical displacement is achieved by a spherical joint mounted on the second base.
 8. The system of claim 1, wherein translating horizontal displacement into vertical displacement is achieved by a planar hinge mounted on the second base.
 9. The system of claim 1, wherein the structure is a tower internal to a building, the tower rigidly fixed to at least one internal wall of the building.
 10. The system of claim 1, wherein the structure is a tower external to a building, the tower rigidly fixed to at least one external wall of the building.
 11. A structural protection system of buildings comprising: a first bearing structure rigidly connected with a first wall of a building, the first bearing structure comprising: a first base; a second base fixed to the ground; a spherical joint mounted on the second base and arranged on the vertical axis of the first bearing structure; and an energy dissipation system disposed between the first base and the second base, the energy dissipation system comprising a first energy dissipation device and a first lever mechanism positioned peripherally to the spherical joint, the first lever mechanism configured to multiply travel of the first energy dissipation device in response to vertical displacement of the first bearing structure.
 12. The system of claim 11, wherein the first lever mechanism comprises: a first lever pivoted at a fulcrum at the second base; and a second lever, each of the second lever and the first energy dissipation device having a first end pivoted at the first base and a second end pivoted at the first lever.
 13. The system of claim 12, wherein the fulcrum is in the center of the first lever such that travel of the first energy dissipation device is twice the vertical displacement of the first bearing structure.
 14. The system of claim 12, wherein: a first distance is the distance along the first lever from the fulcrum to the second lever; a second distance is the distance along the first lever from the fulcrum to the first energy dissipation device; the first lever mechanism is further configured such that travel of the first energy dissipation device relative to vertical displacement of the first bearing structure is a function of the ratio of the second distance to the first distance.
 15. The system of claim 11, wherein the first energy dissipation device comprises an energy dissipation means disposed between two rigid rods.
 16. The system of claim 11, wherein the energy dissipation system further comprises a second energy dissipation device and a second lever mechanism positioned peripherally to the spherical joint opposite the first energy dissipation device and the first lever mechanism, the second lever mechanism configured to multiply travel of the second energy dissipation device in response to vertical displacement of the first bearing structure.
 17. The system of claim 11, wherein the first bearing structure is rigidly connected with the building by rigid rods, each rod having a first end connected to the first wall of the building and a second end connected to the first bearing structure.
 18. The system of claim 17, wherein the rigid rods are arranged in horizontal planes corresponding to floors of the building.
 19. The system of claim 11, further comprising a second bearing structure rigidly connected with a second wall of the building.
 20. A structural protection system of buildings comprising: a bearing structure rigidly connected with a wall of a building, the bearing structure comprising: a first base; a second base fixed to the ground; a spherical joint mounted on the second base and arranged on the vertical axis of the bearing structure; and an energy dissipation system disposed between the first base and the second base, the energy dissipation system comprising: a first energy dissipation device and a first lever mechanism positioned peripherally to the spherical joint, the first lever mechanism configured to multiply travel of the energy dissipation device in response to vertical displacement of the bearing structure; and a second energy dissipation device and a second lever mechanism positioned peripherally to the spherical joint opposite the first energy dissipation device and the first lever mechanism, the second lever mechanism configured to multiply travel of the second energy dissipation device in response to vertical displacement of the bearing structure, wherein compression of the first energy dissipation device corresponds to elongation of the second energy dissipation device and elongation of the first energy dissipation device corresponds to compression of the second energy dissipation device. 